Place soy sauce, sugars, garlic, Coca-Cola and pepper into blender. Mix until no large chucks of garlic remain. Slowly add in sesame oil while still blending. Stir in green onion and sesame seeds. Hold cold.
Marinate beef in the Korean marinade for a minimum if 12 hours. Remove beef from marinade using tongs and transfer to holding pan. Discard leftover marinade.
Grill beef on hot grill cooked to medium temperature, about 1 to 2 minutes per side. Cut into riblets.